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A Planet Too Big To Exist

Using a new array of telescopes in Chile, astronomers have discovered a monster planet which challenges the previously-held theory that huge gaseous planets cannot exist in tight orbits around tiny stars. Now they’re scrambling to explain this big-planet-little star combo.

The latest Monthly Notices of the Royal Astronomical Society announced the exciting discovery this week – exciting because this is the first big finding using the Next-Generation Transit Survey (NGTS) whose purpose is to find giant exoplanets orbiting small stars. Baseball fans will recognize this as an example of a rookie hitting a grand slam home run in his first major league at-bat. (This is what happens when big discoveries occur during the World Series.) Its array of fully-robotic small telescopes operate in the 600-900nm band, making them sensitive to bright but relatively small, cool host stars … stars like the aptly named NGTS-1 in the Columba constellation.

The Columba constellation

The shocking aspect of the discovery is the size, composition and location of NGTS-1b – the ‘hot Jupiter’ spinning around NGTS-1. Hot Jupiters have been in the astronomical news recently with the discovery of WASP-12b, a dark giant gas ball that is mysteriously eating the light from its star. If Elon Musk tells you he has no more seats left on his Mars spacecraft but can get you on a trip to a Hot Jupiter – just say “no.”

“The discovery of NGTS-1b was a complete surprise to us — such massive planets were not thought to exist around such small stars. The planet is about 25 percent the radius its host star. This makes is very large compared to its host star! For comparison, Jupiter is only about 10 percent the radius of our sun.”

Daniel Bayliss, lead author of the study, illustrates one of the impossibilities of NGTS-1b – its size. Dwarf stars were not thought to have enough mass of their own to pull together the amount of mass needed to create such monster planets. Impossibility #2 is its incredible closeness to NGTS-1 … NGTS-1b is a mere 2.8 million miles away from its star (Earth is 93 million miles from the Sun) and completes a ‘yearly’ orbit in 62.4 hours or 2.6 Earth days.

NGTS-1b’s size and proximity to its star contributed greatly to its discovery. Astronomers observing NGTS-1 saw it dim every 2.6 days but, unlike Tabby’s star, they quickly determined it was a monster planet and not an alien-built energy-collecting Dyson sphere causing the dimming.

If there’s an astronomer’s creed, it is that “If there’s one, there’s more,” so the researchers at the European Southern Observatory’s Paranal Observatory in the Atacama Desert of Chile will be using the Next-Generation Transit Survey to find more giant hot Jupiters orbiting tiny cool planets.